This invention relates to an electromagnetic coordinate selection device, and more particularly to a multicontact sealed electromagnetic coordinate selection device used in, for example, a communication network of a telephone exchange.
The above-mentioned type of coordinate selection device known to data comprises reed switches or mercury switches provided at the crosspoints of a circuit network like the Ferreed switching system developed by the Bell Research Laboratory of the United States of America. This prior art sealed contact type switching system comprising a plurality of independent unit contacts has the drawbacks that wide variations occur between the operating properties of the respective unit switches, the specific arrangement of said switching system is unadapted for integration, and limitation is imposed on the miniaturization of said switching system, resulting in high manufacturing cost. Therefore, there has been developed, as set forth in the U.S. Pat. No. 3,150,244 a multicontact sealed switching system which is intended for integration of the parts. The switching system of said United States patent is integrated by application of a common plate. However, this switching system has the shortcomings that since contact springs are welded to the inner wall of a container at the corresponding contact portions, assembly work consumes a great deal of time, thermal deformation of the container resulting from said welding gives rise to variations in the contact spaces (namely, an interval between the respective stationary contacts and movable contacts), making it necessary to adjust said contact spaces for each contact portion, signal lines are jointly connected by the container, failing to provide a multicontact sealed electromagnetic coordinate selection device of 2-or-4-line system, rendering the switching system of said United States Patent unadapted to be used as an electromagnetic coordinate selection device for the communication network of a general telephone exchange, and joint connection of a plurality of signal lines by a sealed container gives rise to noticeable isolation loss of high frequency signals due to leakage.
It is accordingly the object of this invention to provide a compact multicontact sealed electromagnetic coordinate selection device which is formed of a smaller number of parts than in the past, enable the crosspoints of a circuit network to be operated uniformly without the necessity of adjusting contact spaces, minimizes isolation loss of high frequency signals and is prominently adapted for general purpose application.